Meeting China’s emissions legislation

There is little doubt that China has become the largest and fastest growing automotive market in the world. Record economic growth means more of the nation’s 1.34 billion people are able to buy vehicles, and last year alone more than 19 million vehicles were sold.

Infineum FBC technology has recently undergone extensive testing in Chinese vehicles using local fuels

Some analysts forecast that by 2030 there could be up to 350 million vehicles on China’s roads. This might be good news for the world’s automakers, but not such good news in terms of pollution and congestion in the cities.

Fuel sulphur influences aftertreatment selection

To curb pollution National China 4 emission limits, equivalent to Euro 4, are expected to be implemented in 2013 for light passenger vehicles, with Euro 5 type level expected in the future.

These emission limits are no surprise to automakers who have already seen them in other regions and have a number of exhaust gas aftertreatment options to ensure their vehicles comply. However, one added complication in China is the country’s variable fuel quality.

The 2012 Infineum Winter Diesel Fuel Quality Survey revealed that the sulphur content of the fuels sampled from China ranged from just under 70 ppm to almost 1400 ppm. This means OEMs must select their pollution abatement system with care to ensure their vehicles not only meet emissions standards, but also offer trouble free operation for their owners regardless of the sulphur level in the fuel.

Diesel particulate filters (DPFs) are one of the exhaust gas aftertreatment options that have been used in some regions of the world as an effective means of reducing both particulate matter and particulate number. These systems can be fitted in the factory to new cars and trucks, or retrofitted to help reduce emissions from older vehicles.

Given the reduction in particulate emissions required by China’s emissions legislation, the use of DPFs in most diesel vehicles in the country seems inevitable.

Particulate filters – how they work

The exhaust gases flow through the porous wall of the DPF and the particulate matter – mainly in the form of soot – is filtered out. The devices are very efficient in controlling this type of noxious emission – trapping more than 95%.

However, this efficiency presents a challenge, because over time the filter fills with soot, which if not removed can lead to excessive backpressure and ultimately vehicle failure.

The DPF is very efficient in controlling particulate matter trapping more than 95%.

The best way to regenerate a DPF is by burning the particulate matter in situ, although this ‘oxidation’ by oxygen alone requires a temperature of >600°C.

Because the exhaust temperature is usually too low to achieve this, fuel is injected into the exhaust to raise the temperature and initiate regeneration. However, this technique leads to an undesirable fuel economy penalty.

The use of catalytic materials, either in the form of precious metals or fuel borne catalysts (FBC), can substantially reduce the temperature of soot ignition, limit its build up on the DPF and aid combustion.

However, some of these systems use platinum group metal-based catalysts, which are notoriously sensitive to sulphur poisoning, making them unsuitable for use with high sulphur fuels. It is essential for Chinese OEMs and operators to ensure that the technology selected to clean up the filters during vehicle operation is effective in local diesel fuels where fuel sulphur levels are very variable.

The fuel borne catalyst system

Infineum FBC introduces an iron-based catalyst directly into the fuel from a small additive tank that is an integral part of the vehicle.

During combustion in the engine, the FBC becomes incorporated into the particulate matter and lowers the soot burn-off temperature by over 150°C, significantly reducing the fuel and time required to achieve full regeneration, and ensuring more complete regeneration is achieved.

Infineum FBC technology has been successfully used in Europe for a number of years in both factory fill and retrofit applications. Unlike precious metal-based catalysed DPF systems, Infineum FBC is highly tolerant to fuel sulphur.

The system provides a number of additional benefits including:

• Fuel consumption savings
• Faster regeneration vs. untreated fuel in retrofit applications
• Slower soot build up vs. untreated fuel in factory fill applications
• Excellent injector deposit control
• Longevity of exhaust system
• No secondary emissions (NO₂ ) generated
• No harms, even after high mileage and under the most severe conditions
• No infrastructure investments required
• Low additive treat rates

Infineum FBC technology has proven performance under the most rigorous testing, including product stability over time, using the most severe conditions in terms of temperature cycles and temperature extremes. Compatibility with market fuels and those containing bio-components has also been confirmed.

Infineum FBC technology has recently undergone extensive testing in Chinese vehicles using local fuels with high and variable sulphur levels in controlled conditions.

Results confirm the suitability of the Infineum FBC solution for the efficient regeneration of DPFs for the Chinese market in retrofit applications.

The results, which can be seen in the chart above, confirm the suitability of the Infineum FBC solution for the efficient regeneration of DPFs for the Chinese market in retrofit applications.

The data also indicate that the technology has the potential to help vehicle manufacturers to meet the stringent targets set by the China 4/IV and 5/V emissions regulations.

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